1 Field of the Invention
The present invention relates to a gas generating composition suitable for an air bag restraining system of automobiles and the like, a molded article thereof, and an inflator for an air bag using the same.
2 Description of the Related Art
As a gas generating agent for an air bag used in a passenger-protecting system in automobiles, a composition using sodium azide has been conventionally used. However, a toxicity to human bodies [LD50(oral-rat)=27 mg/kg]or hazard in handling of sodium azide has been regarded as a serious problem. Therefore, as safe non-azide based gas generating compositions, gas generating compositions containing various nitrogen-containing organic compounds have been developed to replace the above composition.
U.S. Pat. No. 4,909,549 discloses a composition comprising hydrogen-containing tetrazole or triazole compounds and an oxygen-containing oxidizing agent. U.S. Pat. No. 4,370,181 discloses a gas generating composition comprising a hydrogen-free bitetrazole metal salt and an oxygen-free oxidizing agent. U.S. Pat. No. 4,369,079 discloses a gas generating composition comprising a hydrogen-free bitetrazole metal salt and an alkali metal nitrate, an alkali metal nitrite, an alkaline earth metal nitrate, an alkaline earth metal nitrite or a mixture thereof. U.S. Pat. No. 5,542,999 discloses a gas generating agent comprising a fuel such as GZT, TAGN (triaminoguanidine nitrate), NG (nitroguanidine), NTO and the like, a basic copper nitrate, a catalyst for reducing toxic gases and a coolant. U.S. Pat. No. 5,608,183 discloses a gas generating agent comprising a fuel such as guanidine nitrate, a basic copper nitrate and guar gum.
However, the above non-azide based gas generating composition forms residues (mist) after combustion, and thus a filter must be used to prevent the mist from flowing into an air bag. In this case, there is a method wherein the gas generating composition has a composition easily forming slag, after combustion, having a shape adapted to be readily captured by the filter.
U.S. Pat. No. 6,143,102 discloses that silica is added as a slag-forming agent to a composition comprising a fuel such as guanidine nitrate, a basic copper nitrate and a metal oxide such as alumina, to form excellent slag (clinker).
JP-A No. 10-502610 discloses that glass powder is added to a fuel such as a tetrazole compound and strontium nitrate, thereby lowering the combustion temperature, resulting in a reduction in NOx and CO and formation of solid slag.
U.S. Pat. No. 5,104,466 (JP-A 5-70109) discloses that an alkali metal azide, pellets consisting of an oxidizing agent and grains consisting of a silica-containing material are used as a mixture to reduce mist.